In a system which provides for a setting of the aperture of an interchangeable lens from the side of a camera body mechanism, it is not necessary to provide a manual aperture setting member on the lens barrel. But a lens barrel with an aperture setting member is still needed when the aperture setting from the side of the camera body is disabled, such as during reverse photographing. The aperture apparatus which achieves the aperture setting even in case the interlocking between the aperture mechanism in the side of the lens and the aperture setting mechanism in the side of the camera body is broken by use of a bellows and a close-up ring is also reported by the Japanese patent laid open No. 56-75725 and the Published Japanese utility model No. 52-38201. However, the aperture diaphragm is set by the setting Fthe side of the camera body is carried out, such an aperture setting member is unnecessary for a greater number of the users who do not want to make use of reverse photographing or do not use bellow, and for such users the use of an interchangeable lens which includes an aperture setting member entails increase of increased cost, size and weight of the interchangeable lens. But if the aperture setting member is eliminated for this reason, wide application of the interchangeable lens is lost. However it is disadvantageous to the manufacturer to have to make both interchangeable lenses which have aperture setting members thereon and lenses which do not.